Have You Experienced A Sudden Increase In Body Weight?


I am sure I am not the only one who has stepped on the scale in the morning just to shout out WTF?!?

So does any of these cases sound familiar?

1. After a weekend of loosely tracking your macros, you come home weighing up to a few kilos heavier.

2. You ate at a restaurant and your weight was increased by 1kg the next day despite accounting for the macros.

3. You lost weight easily the first week, but now the weight loss has slowed down.

4. After losing weight steadily for a few weeks, the weight loss suddenly stopped.

5. Despite being in a calorie deficit, all of a sudden, your weight starts to increase.

I am pretty certain that we’ve all experienced one of these at least to a certain extent.

Now, one of the most common reactions in the first and second case is for people to think that they have ruined their diet, making them give up and quit. Obviously, the diet is not working! Or?

In the third, fourth and fifth case, people often slash their calories even more because, clearly, they are eating too much. Or are they?

Though these reactions are completely understandable, the truth is that you need to remain calm and not freak out!


Body weight fluctuations are very common and something that we all experience from time to time and often it is due to a change in water balance in the body. NOT a sudden gain or loss of fat. This change in body weight can have several causes and one of them may be an increase in carbohydrates.

This will generally happen whenever we either:

a) start dieting (reduce calories and carbs)

b) take a break from dieting (increase calories and carbs)

c) have a spike in carb intake (e.g. refeed day)

d) or have a spike in sodium intake (e.g. restaurant meal)

Carbs are stored as glycogen in our bodies and 1g of glycogen holds ~3g of water. The glycogen is stored to a large degree in our muscles and as such they are made up of ~70-80% water.When start dieting we normally reduce the amount of carb (and fat) that we eat. As we are eating fewer carbs, there's less glycogen and water in our muscles and we drop body weight quickly. However, this 'water loss' should not be mistaken for loss of body fat!

This is why most people drop the first few kilos when they start a diet >>> it’s mostly water!!!

So, if you lost a few kilos in the first week that you started dieting, and then half a kilo per week after, it’s reasonable to assume that the weight loss in the first week was mostly water. This doesn't mean that you should be losing weight at this rate moving forward and any weight loss is still progress. (Case 3)

On the other hand, when we eat more carbs than normal, e.g. when we take a diet break or when we have a refeed day, our bodies will hold more water, giving us the impression that we’ve gained a lot of fat. Which is not true! (Case 1)

This is the opposite effect to when we start dieting, and sometimes you regain all the weight lost in the first week, or at least some of it.

But it is not only carbs that can have an effect on your water balance. For instance, when you eat at a restaurant (Case 1), although you may have accounted for the macros (Case 2), restaurant meals normally contain higher levels of sodium which in turn can cause water retention. As a result, although you haven’t over-consumed calories, the sudden weight gain caused by water may make you think that you've gained body fat.


In regards to cases 4 and 5, the weight increase may be due to the increase in cortisol that tends to occur in a calorie deficit. Although it may sound counter-intuitive, having a diet break will assist in reducing the negative hormonal changes to a calorie reduction. So if you have been in a calorie deficit for a while and haven't had a proper diet break, it may just be what you need!

So don’t let temporary fluctuations in water balance freak you out.

But can a sudden weight gain be fat gain?

It is possible, but not likely. The most likely explanation is that you gained water weight especially if you've had an increase of carbohydrate or sodium intake, or if you've been in a calorie deficit for a while. Then it may be an indication that you may need a diet break to help reverse the increased cortisol levels seen in a calorie deficit!

Diet Smart. Not Hard.

Coach Inger